Captivating Cardinal Beetles

Michela Sisti is a volunteer with the Museum’s Entomology Digitisation project. Originally from Canada, she now lives in Oxford. Like many people, she has loved all sorts of creatures from the time she was a child, but the recent lockdowns really brought her close to the natural world again.

She has taken a break from helping to make images of our entomology specimens available online to tell us about one of her favourite insects: the cardinal beetle.

Can you spot the difference between these two beetles? Their bright red exteriors make each an attractive find for nature-lovers. But if you were a small insect, being able to tell these fiery doppelgangers apart might mean the difference between survival and ending up as lunch. 

On the left-hand side is the Lily Beetle (Lilioceris lilii), a lifelong leaf-eater. While it might be the bane of some gardeners, other insects have no need to fear its presence. The character on the right is a Cardinal Beetle, a natural born predator capable of hunting other invertebrates right from the larval stage.

Cardinal Beetles belong to the family, Pyrochroidae. The root ‘pyro’ comes from the Greek word for fire. (Think pyrotechnics – fireworks.) The one I snapped in this photo is a Black-headed Cardinal Beetle (Pyrochroa coccinea) and is found mainly in the south of Britain. Its two cousin species are the Red-headed Cardinal Beetle (by far the most common of the trio) and the Scarce Cardinal Beetle.

On a warm clear day in late spring, you might glimpse one of these sleek hunters perched on a flower petal, soaking in the sunlight. Like many insects, Cardinal Beetles use the sun’s rays to regulate the temperature of their bodies. But there is another reason why these beetles like to idle about on flowers. Flowers attract pollinators and the Cardinal Beetle is poised for ambush. When the moment is ripe it darts forward, sinking its pincer-like mandibles into its prey.

I spotted this incredible insect shortly before I began volunteering with Oxford University’s Museum of Natural History’s Entomology Digitization project. You might say my encounter gave me the bug.

So how to distinguish a Cardinal Beetle from a Lily Beetle? Lily Beetles are rounder with dimpled cases. Cardinal Beetles have larger, narrower bodies and distinctive toothed antennae.

Find out more:

Pyrochroidae | UK Beetle Recording. (n.d.). Coleoptera.org.uk. Retrieved 10 October 2021, from www.coleoptera.org.uk/family/pyrochroidae

Red-headed cardinal beetle | The Wildlife Trusts. (n.d.). The Wildlife Trusts. Retrieved 10 October 2021, from www.wildlifetrusts.org/wildlife-explorer/invertebrates/beetles/red-headed-cardinal-beetle

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